TNF-α induces autophagy through ERK1/2 pathway to regulate apoptosis in neonatal necrotizing enterocolitis model cells IEC-6

Necrotizing enterocolitis (NEC) is a potentially fatal illness in premature neonates. Tumor necrosis factor-α (TNF-α) and autophagy are associated with the pathogenesis of NEC. This study aimed to explore whether TNF-α might regulate apoptosis in neonatal NEC model cells IEC-6 via regulation of autophagy. NEC rat model was induced by hand feeding and exposure to asphyxia/cold-stress for histologic examination. The NEC in vitro model (IEC-6/NEC cells) was established by stimulating the intestinal epithelial cell line IEC-6 with lipopolysaccharide (LPS, 100 μg/mL) for 3 h to investigate the effects of TNF-α on IEC-6 proliferation and apoptosis. In this study, NEC rats showed decreased proliferating cell nuclear antigen (PCNA) expression, increased TUNEL-positive cells, higher expression of TNF-α, p-ERK1/2, and autophagy-related proteins in rat small intestine compared with their controls. Additionally, the LPS-stimulated IEC-6/NEC cells showed a significantly decreased proliferation and increased apoptosis compared with the control cells. Furthermore, the LPS-stimulated IEC-6/NEC cells exhibited enhanced autophagy level, as evidenced by a dose-dependent increase in Beclin-1 protein expression, LC3II/LC3I ratio and accumulation of MDC-positive autophagic vacuoles. Moreover, inhibition of autophagy by wortmannin or LY294002 significantly abolished the LPS-mediated decreased proliferation and increased apoptosis of IEC-6/NEC cells. Results also showed that inhibition of ERK1/2 pathway using U0126 significantly inhibited TNF-α-induced autophagy. Furthermore, the TNF-α-mediated inhibition of IEC-6 proliferation and promotion of IEC-6 apoptosis was abolished by U0126. Our findings demonstrated that TNF-α might induce autophagy through ERK1/2 pathway to regulate apoptosis in neonatal NEC cells IEC-6. Our study enhances our understanding of neonatal NEC pathogenesis.     

TNF—α对哮喘模型大鼠气道平滑肌细胞增殖及ERK1／2活性的影响

目的探讨TNF—α对哮喘大鼠气道平滑肌细胞（ASMCs）增殖及对ASMCs上ERK1／2mRNA、p-ERK1／2表达水平的影响。方法通过对哮喘模型大鼠ASMCs培养,分别以0．2μg／L、1．0μg/L、20μg/L TNF-α干预ASMCs生长。采用流式细胞仪、MTT法检测ASMCs增殖情况,观察不同浓度TNF—α对ASMCs增殖的影响。RT-PCR检测ASMCs上ERK1／2mRNA表达,免疫细胞化学染色法检测磷酸化ERK1／2蛋白的表达及定位。结果哮喘组ASMCsS期比例、A值、ERK1／2mRNA、p-ERK1／2蛋白的表达量分别为（34．45±2．08）％、（0．550±0．010）、（0．995±0．118）、（130．77±4．16）,与对照组（11．17±0．96）％、（0．292±0．008）、（0．576±0．098）、（163．82±1．38）比较均显著增高（均P〈0．01）。各TNF—α干预组ASMCs的S期比例、A值、ERK1／2mRNA和p-ERK1／2蛋白表达量与哮喘组比较均显著降低（均P〈0．01）,0．2μg/L和1．0μg／LTN-α组p-ERK1／2蛋白表达量高于对照组（P〈0．01）,20μg／L TNF-α组p-ERK1／2蛋白表达量与对照组比较无差异（P〉0．05）。结论与正常鼠相比,慢性哮喘大鼠气道平滑肌细胞增殖明显,处于S期的细胞比例明显增高。经TNF—α干预后,慢性哮喘大鼠气道平滑肌细胞处于S期的细胞比例减少,增殖减弱,TNF-α可能抑制慢性哮喘大鼠气道平滑肌细胞增殖。TNF—α可下调慢性哮喘大鼠气道平滑肌细胞上ERK1／2mRNA及p-ERK1／2表达,TNF-α可能通过抑制ERK信号转导通道的活性对气道平滑肌细胞的增殖进行调控。     

SPARCL1通过MEK/ERK信号通路调节非小细胞肺癌细胞的增殖、凋亡和侵袭

摘要 目的：分析富含半胱氨酸的酸性分泌蛋白类似蛋白1（SPARCL1）对非小细胞肺癌（NSCLC）细胞增殖、凋亡、侵袭的影响,并探讨分裂原活化抑制剂（MEK）/细胞外调节蛋白激酶（ERK）通路在其中发挥的作用。方法：收集2019年9月~2021年6月期间本院接受手术治疗的84例NSCLC患者癌组织与相应癌旁组织,实时定量逆转录聚合酶链反应（qRT-PCR）法测定并比较各组织以及正常肺上皮细胞HBEpiC、NSCLC细胞A549、HCC827、H1299、H292中SPARCL1 信使RNA（mRNA）表达水平,选取A549、HCC827培养并分组,分为对照组、NC siRNA组、SPARCL1 siRNA组、U0126组（MEK/ERK特异性抑制剂）、SPARCL1 siRNA加U0126组,细胞计数法（CCK8）以及平板克隆法测定A549、HCC827细胞增殖,流式细胞仪测定A549、HCC827细胞凋亡,Transwell小室法测定A549、HCC827细胞侵袭能力,蛋白质印迹法（western blot）检测SPARCL1、p-MEK、MEK、p-ERK1/2、ERK1/2蛋白表达。结果：SPARCL1在NSCLC组织中mRNA表达水平低于癌旁组织（P＜0.05）;与HBEpiC细胞相比,NSCLC细胞A549、HCC827、H1299、H292细胞中SPARCL1 mRNA表达水平降低（P＜0.05）;与对照组相比,SPARCL1 siRNA组A549、HCC827细胞SPARCL1 mRNA表达水平与蛋白表达、凋亡率降低（P＜0.05）,OD₄₅₀、克隆形成数、侵袭细胞数、p-MEK/MEK、p-ERK1/2/ERK1/2蛋白表达升高（P＜0.05）,U0126组A549、HCC827细胞SPARCL1 mRNA表达水平与蛋白表达、凋亡率升高（P＜0.05）,OD₄₅₀、克隆形成数、侵袭细胞数、p-MEK/MEK、p-ERK1/2/ERK1/2蛋白表达降低（P＜0.05）;与SPARCL1 siRNA组相比,SPARCL1 siRNA加U0126组A549、HCC827细胞SPARCL1 mRNA表达水平与蛋白表达、凋亡率升高（P＜0.05）,OD₄₅₀、克隆形成数、侵袭细胞数、p-MEK/MEK、p-ERK1/2/ERK1/2蛋白表达降低（P＜0.05）。结论：SPARCL1可能通过调控MEK/ERK通路影响NSCLC A549、HCC827细胞增殖、侵袭与凋亡。     

大黄酸调节Ras/ERK信号通路对肝细胞癌细胞增殖、迁移和侵袭的影响

摘要 目的：探讨大黄酸调节大鼠肉瘤蛋白（Ras）/胞外信号调控激酶（ERK）信号通路对肝细胞癌（HCC）细胞增殖、迁移和侵袭的影响。方法：使用不同浓度（0、12.50、25、50、100、150、200 mol/L）大黄酸处理HepG2细胞,检测细胞活性,筛选最佳大黄酸浓度。将细胞分为对照组、大黄酸低、中、高浓度组、大黄酸高浓度+Ras/ERK激活剂组（大黄酸高浓度+ML-099组）,分别检测各组细胞集落形成数、划痕愈合率、细胞侵袭数和Ras、p-ERK、ERK蛋白表达。结果：大黄酸以浓度和时间依赖性降低HepG2细胞活性（P<0.05）,选用25、50、100 mol/L处理HepG2细胞24 h用于后续实验;与对照组比较,大黄酸低、中、高浓度组细胞集落形成数、G0/G1细胞比例、细胞划痕愈合率、细胞侵袭数和原癌基因（c-Myc）、细胞周期蛋白D1（CyclinD1）、Ras、p-ERK/ERK蛋白表达呈浓度依赖性降低,S期和G2/M细胞比例、p53蛋白表达呈浓度依赖性增加（P<0.05）;与大黄酸高浓度组比较,大黄酸高浓度+ML-099组细胞集落形成数、G0/G1细胞比例、细胞划痕愈合率、细胞侵袭数和c-Myc、CyclinD1、Ras、p-ERK/ERK蛋白表达显著增加,S期和G2/M细胞比例、p53蛋白表达显著降低（P<0.05）。结论：大黄酸可能通过抑制Ras/ERK信号通路抑制HCC细胞增殖、迁移和侵袭。     

Cytokine effects on cell survival and death of A549 lung carcinoma cells

PurposeIL-13, TNF-α and IL-1β have various effects on lung cancer growth and death, but the signaling pathways mediating these effects have not been extensively analyzed. Therefore, the effects of IL-13, TNF-α and IL-1β alone, and in combination with Fas, on cell viability and death as well as major signaling pathways involved in these effects were investigated in A549 lung carcinoma cells.ResultsUsing MTT and flow cytometry, IL-13, TNF-α and IL-1β pretreatment decreased Fas-induced cell death. These anti-cell death effects were attenuated by pretreatment with inhibitors of Nuclear factor-κB [NF-κB], Phoshatidylinositole-3 kinase [PI3-K], JNK, p38 and ERK1/2 pathways.Using Western blot, IL-13, TNF-α and IL-1β treated cells showed time-dependent expression of p-ERK1/2, p-p38, p-JNK, p-Akt and p-IκBα proteins, decreased IκBα protein expression, no cleavage of Caspase-3 and PARP1 proteins and no notable alterations of Fas protein. IL-13 and TNF-α treated cells showed time-dependent increase of FLIP_L expression.ConclusionIL-13, TNF-α and IL-1β attenuate the pro-cell death effects of Fas on A549 cells, at least partially, by pathways involving the NF-κB, PI3-K and MAP kinases, but not by alterations of Fas protein expression. The IL-13 and TNF-α cell survival effects may also be due to increased expression of FLIP_L protein.     

Ginsenoside-Rg2 affects cell growth via regulating ROS-mediated AMPK activation and cell cycle in MCF-7 cells

BackgroundGinsenoside-Rg2 (G-Rg2) is a protopanaxatriol-type ginsenoside isolated from ginseng. It has been found to exhibit various pharmacological effects, including antioxidant, anti-inflammatory, and anticancer effects.PurposeThis study aimed to investigate the anticancer effects of G-Rg2 on estrogen receptor-positive MCF-7 breast cancer (BC) cells, and the underlying mechanisms involving in reactive oxygen species (ROS) production.Study design/MethodsCell viability, cell cycle distribution, apoptosis, and ROS production were measured following exposure to G-Rg2. The protein expression levels of p-ERK1/2, p-Akt, PARP, p-Rb, cyclin D1, CDK6, and p-AMPK were quantified using western blot analysis. The in vivo activity of G-Rg2 was assessed in a xenograft model. Immunohistochemistry staining for p-Rb and p-AMPK was performed in tumor tissues.ResultsG-Rg2 significantly decreased cell viability but increased cell apoptosis. In MCF-7 cells, G-Rg2 increased ROS production by inhibiting ERK1/2 and Akt activation. G-Rg2-induced ROS induced G0/G1 cell cycle arrest and AMPK phosphorylation. In the xenograft model, the 5 mg/kg G-Rg2-treated group showed decreased tumor volume and weight, similar to the 5 mg/kg 4-OHT-treated group, compared to the control group. Immunohistochemistry staining showed that G-Rg2 treatment decreased Rb phosphorylation, while increasing AMPK phosphorylation in tumor tissues.ConclusionG-Rg2 has potential anticancer effects by increasing the ROS-AMPK signaling pathway and inhibiting ERK1/2 and Akt activation-mediated cell proliferation and cell cycle progression in MCF-7 BC cells.     

RACK1对硼替佐米诱导的多发性骨髓瘤细胞凋亡及MAPK/ERK通路的影响

目的:探讨蛋白激酶C受体(Receptor for activated C kinase1,RACK1)对硼替佐米(Bortezomi,Bor)诱导的多发性骨髓瘤(Multiple myeloma,MM)细胞凋亡及MAPK/ERK通路的影响。方法:选取6例岳阳市第一人民医院收治的MM患者及6名正常体检者,用实时荧光定量PCR检测血浆及人MM细胞系中RACK1 m RNA的表达。将MM细胞分为3组:对照组(不干预)、Bor组(75n M的Bor干预12 h)和Bor+siRACK1组(RACK1 si RNA转染24 h后再行Bor干预)。CCK-8法检测各组细胞中的细胞存活率,Hoechest 33342染色检测细胞凋亡,Western Blot检测MAPK/ERK通路相关蛋白表达。结果:与正常体检者相比,MM患者血浆及MM细胞系中RACK1 m RNA表达显著增加(P0.05)。Bor作用12 h、24 h和48 h可显著降低MM细胞的存活率(P0.05)。与对照组相比,Bor组和Bor+siRACK1组细胞存活率显著降低,Bor+siRACK1组细胞存活率明显高于Bor组(P0.05)。Hoechest 33342染色显示对照组细胞核染色均一,未见凋亡小体,Bor组见少量凋亡小体,而Bor+siRACK1组细胞见大量凋亡小体,表现为核固缩或碎块状;与对照组相比,Bor组和Bor+siRACK1组细胞中多发性骨髓瘤细胞凋亡率显著增加(P0.05),Bor+siRACK1组多发性骨髓瘤细胞凋亡率明显高于Bor组(P0.05)。三组间多发性骨髓瘤细胞凋亡率对比差异有统计学意义(P0.05)。与对照组相比,Bor组和Bor+siRACK1组细胞中p-P38和p-ERK的表达显著降低,而Bor+siRACK1组p-P38和p-ERK的表达低于Bor组(P0.05),3组间P38和ERK的表达对比差异无统计学意义(P0.05)。结论:RACK1沉默可增强Bor诱导的MM细胞凋亡及生长抑制,其机制可能与MAPK/ERK途径抑制有关。     

麦没食子儿茶素没食子酸酯对TNF-α诱导的内皮细胞中PAI-1表达的影响及机制研究

目的探讨绿茶的主要成分麦没食子儿茶素没食子酸酯(EGCG)在血管内皮细胞中对肿瘤坏死因子-α(TNF-α)所诱导的纤溶酶原激活物抑制物-1(PAI-1)表达的影响及机制。方法利用人脐静脉内皮细胞体外培养方法,分别与TNF-α和/或EGCG孵育,运用蛋白免疫印迹方法检测内皮细胞中磷酸化细胞外调节蛋白激酶1/2(p-ERK1/2)和肿瘤坏死因子受体1(TNFR1)蛋白表达,应用酶联免疫吸附法方法检测细胞液中PAI-1水平。结果 TNF-α以浓度依赖和时间依赖方式增加内皮细胞中PAI-1的表达。EGCG可抑制TNF-α所诱导的PAI-1的表达,并可抑制ERK1/2磷酸化。TNF-α的刺激可使TN-FR1表达明显减少,而EGCG可抑制这一作用。结论 EGCG可能通过抑制ERK1/2的磷酸化,从而抑制TNF-α所诱导的PAI-1的表达,同时可减少TNF-α对TNFR1的抑制作用,在改善肥胖、胰岛素抵抗及相关心血管疾病中起着重要作用。     

Downregulation of microRNA-144 inhibits proliferation and promotes the apoptosis of myelodysplastic syndrome cells through the activation of the AKAP12-dependent ERK1/2 signaling pathway

BackgroundMyelodysplastic syndromes (MDS) represent a family of hematopoietic stem cell disorders characterized by ineffective hematopoiesis. While the functions of many microRNAs have been identified in MDS, microRNA-144 (miR-144) remains poorly understood. Thus, the aim of the present study was to determine the effects of miR-144 on cell proliferation and apoptosis in MDS cells and mechanism thereof.MethodsMDS-related microarrays were used for screening differentially expressed genes in MDS. The relationship between miR-144 and A-kinase anchoring protein 12 (AKAP12) was determined by a dual luciferase reporter gene assay. Subsequently, gain- and loss-function approaches were used to assess the effects of miR-144 and AKAP12 on cell proliferation, cell cycle and cell apoptosis by MTT assay and flow cytometry. Following the induction of a mouse model with MDS, the tumor tissues were extract for evaluation of apoptosis and the expression of miR-144, AKAP12, and the relevant genes associated with extracellular-regulated protein kinases 1/2 (ERK1/2) signaling pathway and apoptosis.ResultsWe observed significantly diminished expression of AKAP12 in MDS samples. miR-144 directly bound to AKAP12 3′UTR and reduced its expression in hematopoietic cells. Downregulation of miR-144 or upregulation of AKAP12 was observed to prolong cell cycle, inhibit cell proliferation, and induce apoptosis, accompanied by increased expression of AKAP12, p-ERK1/2, caspase-3, caspase-9, Bax, and p53, as well as decreased expression of Bcl-2. The transplanted tumors in mice with down-regulated miR-144 exhibited a lower mean tumor diameter and weight, and increased apoptosis index and expression of AKAP12 and ERK1/2.ConclusionTaken together, these studies demonstrate the stimulative role of miR-144 in MDS progression by regulating AKAP12-dependent ERK1/2 signaling pathway.     

Ca~(2+)信号在肿瘤坏死因子-α诱导心肌肥大PI3-K信号途径中的作用

目的:研究Ca2+信号在肿瘤坏死因子-α(TNF-α)诱导心肌细胞肥大PI3-K信号途径中的作用。方法:Lowry法测心肌细胞蛋白含量;计算机图像分析系统测心肌细胞体积;[3H]-亮氨酸掺入法测心肌细胞蛋白合成;Till阳离子测定系统观察胞内[Ca2+]i瞬变。结果:①TNF-α(100μg/L)明显诱导心肌细胞蛋白含量、蛋白合成及体积的增加,PI3-K特异性抑制剂LY294002(50μmol/L)明显抑制TNF-α诱导的心肌肥大,但对正常心肌细胞生长无影响。L型Ca2+通道阻断剂verapamil(1μmol/L)对TNF-α诱导的心肌肥大无明显影响。②TNF-α引起心肌细胞内钙离子浓度([Ca2+]i)瞬间变化幅度增高,LY294002明显降低TNF-α诱导的上述改变,L型Ca2+通道阻断剂verapamil(1μmol/L)对TNF-α引起的变化无明显影响。结论:PI3-K可能通过引起心肌细胞[Ca2+]i升高参与TNF-α诱导的心肌细胞肥大,但与L型Ca2+通道无关。     

Dehydroevodiamine ameliorates indomethacin-induced gastric injury via inhibition of ERK and p38 signaling pathway

BackgroundDehydroevodiamine (DHE), a pivotal quinazoline alkaloid isolated from Fructus Evodiae (Tetradium ruticarpum (A. Juss.) Hartley), has various pharmacological effects. However, the effect of DHE on gastric injury is still uncharted.PurposeTo clarify the pharmacological effect and mechanism of DHE on gastric injury (GI) induced by indomethacin (IDO).Study designThe gastric injury was induced in rat by oral administration of 5 mg/kg IDO for 7 days. Then the rats were treated with DHE (10, 20, 40 mg/kg, ig) for 7 days.MethodsThe changes of food intake, body weight, gastric pH and general state observation were determined. And HE staining and AB-PAS staining was analyzed. Then, the inflammatory infiltration of gastric tissue was observed through MPO immunohistochemical approach, and the expression of TNF-α, IL-6 and IL-10 were measured. Furthermore, the levels of proteins ERK, p-ERK, P38, p-P38, JNK and p-JNK were determined to elucidate the molecular mechanism of DHE.ResultsDHE alleviated food intake reduction, weight loss and gastric injury induced by IDO and made gastric pH and mucosal thickness return to normal. In addition, DHE could down regulate the expression of MPO, TNF-α and IL-6 and up regulate the expression of IL-10 to reduce the damage induced by inflammatory, and create a healing environment. Furthermore, DHE could significantly inhibit the phosphorylation of ERK and p38 not JNK.ConclusionDHE ameliorated dyspepsia, inflammatory infiltration and tissue damage induced by IDO through ERK and p38 signaling pathways rather than JNK pathway.     

Protective effect of Homer 1a on tumor necrosis factor-α with cycloheximide-induced apoptosis is mediated by mitogen-activated protein kinase pathways

Although Homer 1, of the postsynaptic density, regulates apoptosis, the signaling mechanisms are not fully elucidated. In this study, we found that tumor necrosis factor-α (TNF-α)/cycloheximide (CHX) treatment transiently increased Homer 1a (the short variant of Homer 1), but did not affect Homer 1b/c (the long variant of Homer 1). Overexpression of Homer 1a blocked TNF-α/CHX-induced apoptotic cell death, whereas inhibition of Homer 1a induction enhanced the pro-apoptotic effect of TNF-α/CHX treatment. Moreover, brain-derived neurotrophic factor, as a potential activator of endogenous Homer 1a, inhibited apoptotic cell death after TNF-α/CHX treatment through induction of Homer 1a. Since three major mitogen-activated protein kinase (MAPK) pathways have important roles in apoptosis, we examined if Homer 1a is involved in the effects of MAPK pathways on apoptosis. It was shown that inhibition of the ERK1/2 pathway increased the expression and the protective effect of Homer 1a, but inhibition of the p38 pathway produced the opposite effect. Cross-talk among MAPK pathways was also associated with the regulation of Homer 1a during apoptotic cell death. Blocking the p38 pathway increased the activity in the ERK1/2 pathway, while inhibition of ERK1/2 pathway abolished the effect of p38 inhibitor on Homer 1a. Furthermore, Homer 1a reversely affected the activation of MAPK pathways. These findings suggest that Homer 1a plays an important role in the prevention of apoptotic cell death and contributes to distinct regulatory effects of MAPK pathways on apoptotic cell death.     

High glucose-induced repression of RAR/RXR in cardiomyocytes is mediated through oxidative stress/JNK signaling

The biological actions of retinoids are mediated by nuclear retinoic acid receptors (RARs) and retinoid X receptors (RXRs). We have recently reported that decreased expression of RARα and RXRα has an important role in high glucose (HG)-induced cardiomyocyte apoptosis. However, the regulatory mechanisms of HG effects on RARα and RXRα remain unclear. Using neonatal cardiomyocytes, we found that ligand-induced promoter activity of RAR and RXR was significantly suppressed by HG. HG promoted protein destabilization and serine-phosphorylation of RARα and RXRα. Proteasome inhibitor MG132 blocked the inhibitory effect of HG on RARα and RXRα. Inhibition of intracellular reactive oxidative species (ROS) abolished the HG effect. In contrast, H(2)O(2) stimulation suppressed the expression and ligand-induced promoter activity of RARα and RXRα. HG promoted phosphorylation of ERK1/2, JNK and p38 MAP kinases, which was abrogated by an ROS inhibitor. Inhibition of JNK, but not ERK and p38 activity, reversed HG effects on RARα and RXRα. Activation of JNK by over expressing MKK7 and MEKK1, resulted in significant downregulation of RARα and RXRα. Ligand-induced promoter activity of RARα and RXRα was also suppressed by overexpression of MEKK1. HG-induced cardiomyocyte apoptosis was potentiated by activation of JNK, and prevented by all-trans retinoic acid and inhibition of JNK. Silencing the expression of RARα and RXRα activated the JNK pathway. In conclusion, HG-induced oxidative stress and activation of the JNK pathway negatively regulated expression/activation of RAR and RXR. The impaired RAR/RXR signaling and oxidative stress/JNK pathway forms a vicious circle, which significantly contributes to hyperglycemia induced cardiomyocyte apoptosis.     

APOE2 promotes the development and progression of subretinal neovascularization in age-related macular degeneration via MAPKs signaling pathway

BackgroundNeovascular age-related macular degeneration (nvAMD) is one of the main pathological features of wet AMD. Apolipoprotein E2 is involved in the formation of nvAMD but the molecular mechanism has not been reported.MethodsThe APOE alleles in AMD patients were detected by genotyping. Mouse models were divided into 4 groups according to transfection different gene segments and laser-induced treatment. APOE2, VEGF, PDGF-BB, b-FGF and inflammatory cytokines (including p-NF-κB, TNF-α, IL-1β and IL-6) were tested by ELISA in mice retinal lysate. The formation of nvAMD in the indicated treatment groups at 3rd, 7th and 14th day after laser-induced damage were detected by FFA. Besides, qRT-PCR was used to determine the mRNA levels of p38, JNK and ERK in ARPE-19 cells. Finally, the inflammatory cytokines and MAPK proteins (including P38, p-P38, JNK, p-JNK, ERK and p-ERK) were detected by western blot.ResultsThe statistics of APOE alleles showed that APOE2 allele carriers were more likely to nvAMD. VEGF, PDGF-BB, b-FGF and related inflammatory cytokines were up-regulated significantly after treatment with APOE2, which were reduced after silencing the MAPK family genes, however. Further, the expression levels of neovascular growth factors and inflammatory cytokines were highly consistent between mouse models and ARPE-19 cells. Besides, the phosphorylation levels of p38, JNK and ERK were affected by APOE2.ConclusionnvAMD was affected directly by the overexpression of VEGF, PDGF-BB and b-FGF, which were regulated by APOE2 through activating MAPKs pathway.     

PBK/TOPK在乳腺癌细胞中介导MEK非依赖性ERK激活中作用机制分析

该文探讨了乳腺癌细胞中表皮生长因子(EGF)介导的MEK非依赖性ERK激活通路。Western blot检测EGF刺激下,siRNA抑制MEK1/2后的T47D细胞的p-ERK水平,以验证T47D细胞中存在EGF介导的MEK非依赖性ERK激活的通路。接着使用可能参与MEK非依赖性ERK激活的激酶的小分子抑制剂抑制相关激酶(AC、PKC、Src、PI3K、PDK1和Akt)活性后,检测T47D细胞EGF介导ERK的磷酸化水平。siRNA抑制MEK1/2表达后,T47D细胞在EGF刺激后的仍保留部分p-ERK,即在T47D细胞中,存在EGF介导的MEK非依赖性的ERK磷酸化通路。小分子抑制剂抑制AC、PKC、Src对MEK非依赖性ERK激活途径影响不大。而使用小分子抑制剂抑制PI3K、PDK1和Akt后,ERK的磷酸化水平显著降低,提示PI3K/Akt通路下游的激酶参与T47D中EGF介导的MEK非依赖性ERK激活途径。siRNA干扰PI3K/Akt通路下游PBK/TOPK后并使用U0126抑制MEK功能后,几乎检测不到p-ERK,提示PBK/TOPK参与T47D细胞中EGF介导的MEK非依赖性ERK激活途径。乳腺癌抗雌激素药物耐药株T47D细胞存在EGF介导的MEK非依赖性ERK激活途径,且该途径受PI3K/Akt下游的PBK/TOPK调控。     

肿瘤坏死因子-α诱导心肌肥大中CaN信号通路的作用

目的:研究钙调神经磷酸酶(CaN)信号通路在肿瘤坏死因子-α(TNF-α)诱导心肌细胞肥大中的作用。方法:Lowry法测心肌细胞蛋白含量;计算机图象分析系统测心肌细胞体积;[3H]-亮氨酸掺入法测心肌细胞蛋白合成;Till阳离子测定系统观察胞内[Ca2+]i瞬变;Western blot法测定CaN的表达。结果:①CaN特异性抑制剂CsA(0.2μmol/L)明显抑制TNF-α(100μg/L)诱导的心肌细胞蛋白含量、蛋白合成和细胞体积增大,但对正常心肌细胞生长无影响。②CaN特异性抑制剂CsA(0.2μmol/L)明显降低TNF-α诱导的心肌细胞内钙离子浓度([Ca2+]i)瞬变幅度增高。③TNF-α明显增强心肌细胞内CaN的表达。结论:TNF-α可能通过引起心肌细胞[Ca2+]i升高,促进CaN表达诱导心肌细胞肥大。     

Escherichia coli-induced productions of pro-inflammatory cytokines are regulated by MAP kinases and G-protein but not by Akt: Relationship with phylogenetic groups and resistance patterns

Introduction

We investigated the role of PI3-K, MAP kinases, and heterotrimeric G proteins in inducing cytokines production in human whole blood cultures stimulated by viable Escherichia coli (E. coli) clinical strains.

Materials and methods

We used eight E. coli strains that belong to different phylogenetic groups and presented by different antibiotic resistance patterns. Whole blood from healthy volunteers was incubated at 37 °C for 150 min, with lipopolysaccharide (LPS) from E. coli O111:B4 or selected viable E. coli clinical strains, with or without SB202190 (p38 inhibitor), PD98059 (ERK inhibitor), PTX (pertussis toxin; heterotrimeric G proteins inhibitor), wortmaninn (PI3-K inhibitor). The TNF-α, IL-1β, IL-10 and IFN-γ concentrations were measured in culture supernatants (ELISA).

Results

IL-10 and IFN-γ were not detectable. Susceptible strains induced higher TNF-α and IL-1β productions than β-lactam resistant strains (p < 0.05), with no difference between phylogenetic groups. A transformed strain carrying a plasmid-mediated AmpC-β-lactamase gene (CMY-2) induced lower TNF-α and IL-1β production than the parent wild type strain (p < 0.05). SB202190 (p38 inhibitor) and PD98059 (ERK inhibitor) reduced TNF-α concentrations by, respectively, 80% (p < 0.05) and 50% (p < 0.05). Wortmaninn (PI3-K inhibitor) had no significant effect. PTX (heterotrimeric G proteins inhibitor) altered TNF-α production after viable bacteria stimulation (1.7-fold increase; p < 0.05) but not after LPS (TLR-4) stimulation. Regarding IL-1β, wortmaninn, SB202190 and PTX had no significant effect whereas PD98059 significantly decreased production in whole cell cultures (p < 0.05).

Conclusion

Susceptible strains induce greater TNF-α and IL-1β productions than resistant strains. ERK kinase plays a major role in viable E. coli strains inducing TNF-α and IL-1β production. E. coli exerts an effect on the pertussis toxin-sensitive G-protein through a TLR-4-independent mechanism.     

LncRNA UCA1 protects cardiomyocytes against hypoxia/reoxygenation induced apoptosis through inhibiting miR-143/MDM2/p53 axis

BackgroundlncUCA1 is abundantly expressed in the heart, indicating it may be important in maintaining normal myocardial function. However, the underlying mechanism of lncUCA1 in heart disease, particularly myocardial infarction (MI), is still in its infancy.MethodsLncUCA1 and miR-143 expression were measured in hearts of MI models. Overexpression and knockdown of lncUCA1 in neonatal rat cardiomyocytes were performed to confirm the effects of lncUCA1 in hypoxia-induced apoptosis.ResultsThe expression of lncUCA1 decreased but miR-143 increased inversely in MI heart. Overexpressing lncUCA1 protected cardiomyocytes from H/R induced apoptosis via inhibiting miR-143, which regulates apoptosis by targeting MDM2/p53 pathway. While silencing lncUCA1 caused miR-143 upregulation and H/R-induced apoptosis increase. Moreover, miR-143 was proved to be a competitive target of lncUCA1.ConclusionslncUCA1 might protect cardiomyocyte against H/R induced apoptosis by suppressing miR-143 and modulated the following downstream MDM2/p53 signaling pathway, indicating the therapeutic potential of targeting lncUCA1 for MI.     

A selective estrogen receptor modulator inhibits tumor necrosis factor-α-induced apoptosis through the ERK1/2 signaling pathway in human chondrocytes

Tumor necrosis factor α (TNF-α) is a pleiotropic cytokine mediating inflammatory as well as cell death activities, and is thought to induce chondrocytic chondrolysis in inflammatory and degenerative joint diseases. Selective estrogen receptor modulators (SERMs), such as raloxifene, which are commonly used in clinical settings act as estrogen agonists or antagonists. It is assumed that estrogens have a potential role in cartilage protection; however, the precise molecular mechanism for the protective effects of estrogens is unclear. This study was designed to examine whether raloxifene inhibits TNF-α-induced apoptosis in human chondrocytes and to clarify the mechanisms involved. We also investigated the signaling pathways responsible for the anti-apoptotic effect of raloxifene. Apoptosis in chondrocytes was determined by DNA fragmentation assay and caspase-3 activation. Raloxifene significantly inhibited TNF-α-induced caspase-3 activation and cell DNA fragmentation levels in chondrocytes. The inhibitory effect of raloxifene was abolished by the estrogen receptor antagonist ICI 182,780. Extracellular signal-regulated kinase 1/2 (ERK1/2) regulates apoptosis, acting as an apoptotic or anti-apoptotic signal. TNF-α-induced apoptosis was significantly enhanced by the ERK1/2 pathway inhibitor PD98059. Raloxifene stimulated a further increase in ERK1/2 phosphorylation in TNF-α-treated chondrocytes. Furthermore, the anti-apoptotic effects of raloxifene were inhibited by PD98059. In addition, the anti-apoptotic effects of raloxifene were completely abolished in ERK1/2 siRNA-treated chondrocytes. These results suggest that raloxifene prevents caspase-3-dependent apoptosis induced by TNF-α in human chondrocytes by activating estrogen receptors and the ERK1/2 signaling pathway.